We have complete and submitted a major paper describing the number and location of the cells that innervate the stapedius muscle in cats. This has been sent to the Journal of Comparative Neurology. We have begun working on a paper that will describe the course of these stapedius fibers in the brainstem. Another paper is planned which will describe characteristics of the stapedius neurons. Several experiments have been performed combining horseradish peroxidase with radioactive tracers. The iron dextran technique was tried. Fluorescent dyes and immunologically located lectins are being evaluated now. We are making injections into the stapedius muscle with one tracer and into the cochlear nucleus with the other. Dr. Kobler is developing techniques for locating the stapedius neurons physiologically and will then label them. Our project, defining the neuroanatomy of the stapedius muscle acoustic reflex, is progessing.